[Xen-devel] Linux Guest Crash on stress test of memory sharing

[MaoXiaoyun <tinnycloud@xxxxxxxxxxx>]

Hi:
 
       Follow George's suggestion to summit the bug in this new thread.
 
       Start 24 linux HVMS on a physical host, each of them reboot through "xm reboot" every 30minutes.
       After several hours, some of the HVM will crash.
 
       All of the crash HVM are stopped during booting.
       The bug still exists even I forbid page sharing by cheating tapdisk that xc_memshr_nominate_gref()
       return failure. No bug if memory sharing is disabled.
       (This means only mem_sharing_nominate_page() are called, and in mem_sharing_nominate_page()
        page type is set to p2m_shared, so later it needs to be unshared when someone try to use it)
 
       I remember there is a call routine in memory sharing,
       hvm_hap_nested_page_fault()->mem_sharing_unshare_page() 
       compare to the crash dump, it might indicates some connections.
 
DomU kernel is from ftp://ftp.redhat.com/pub/redhat/linux/enterprise/5Server/en/os/SRPMS/kernel-2.6.18-164.el5.src.rpm
Xen version: 4.0.0
 
crash dump stack :
 
crash> bt -l
PID: 2422   TASK: ffff810013b40860  CPU: 1   COMMAND: "setfont"
 #0 [ffff810012cef900] xen_panic_event at ffffffff88001d28
 #1 [ffff810012cef920] notifier_call_chain at ffffffff80066eaa
    /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/kernel/sys.c: 146
 #2 [ffff810012cef940] panic at ffffffff8009094a
    /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/kernel/panic.c: 101
 #3 [ffff810012cefa30] oops_end at ffffffff80064fca
    /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/arch/x86_64/kernel/traps.c: 539
 #4 [ffff810012cefa40] do_page_fault at ffffffff80066dc0
    /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/arch/x86_64/mm/fault.c: 591
 #5 [ffff810012cefb30] error_exit at ffffffff8005dde9
    [exception RIP: vgacon_do_font_op+435]
    RIP: ff ffffff8005162d  RSP: ffff810012cefbe8  RFLAGS: 00010287
    RAX: ffff8100000a6000  RBX: ffffffff804b3740  RCX: ffff8100000a4ae0
    RDX: ffff810012d16ae1  RSI: ffff810012d14000  RDI: ffffffff803244c4
    RBP: ffff810012d14000   R8: d0d6999996000000   R9: 0000009090b0b0ff
    R10: 0000000000000000  R11: 0000000000000000  R12: 0000000000000004
    R13: 0000000000000001  R14: 0000000000000001  R15: 000000000000000e
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 #6 [ffff810012cefc20] vgacon_font_set at ffffffff8016bec5
    /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/drivers/video/console/vgacon.c: 1238
 #7 [ffff810012cefc60] con_font_op at ffffffff801aa86b
    /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/drivers/char /vt.c: 3645
 #8 [ffff810012cefcd0] vt_ioctl at ffffffff801a5af4
    /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/drivers/char/vt_ioctl.c: 965
 #9 [ffff810012cefd70] tty_ioctl at ffffffff80038a2c
    /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/drivers/char/tty_io.c: 3340
#10 [ffff810012cefeb0] do_ioctl at ffffffff800420d9
    /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/fs/ioctl.c: 39
#11 [ffff810012cefed0] vfs_ioctl at ffffffff800302ce
    /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/fs/ioctl.c: 500
#12 [ffff810012ceff40] sys_ioctl at ffffffff8004c766
    /usr/src/redhat/BUILD/kernel-2.6.18/linux-2.6.18.x86_64/fs/ioctl.c: 520
#13 [ffff810012ceff80] tracesys at ffffffff8005d28d (via system_call)
    RIP: 00000039294cc557  RSP: 00007fff1a57ed98  RFLAGS: 00000246
    RAX: f fffffffffffffda  RBX: ffffffff8005d28d  RCX: ffffffffffffffff
    RDX: 00007fff1a57edb0  RSI: 0000000000004b72  RDI: 0000000000000003
    RBP: 000000001e33dab0   R8: 0000000000000010   R9: 0000000000800000
    R10: 0000000000000000  R11: 0000000000000246  R12: 0000000000000010
    R13: 0000000000000200  R14: 0000000000000008  R15: 0000000000000008
    ORIG_RAX: 0000000000000010  CS: 0033  SS: 002b

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